Introduction
Tempel.el is a package written by Daniel Mendler, a developer of many projects (many of which are fantastic Emacs packages). It provides a way to define text snippets with lisp-like syntax. You can embed Emacs Lisp code into the snippets to obtain programmatically obtained efficiency.
It's based off of the ancient tempo library from Emacs, but it's modernized and updated. I've never tried plain tempo, but it's one of Emacs's several ancient text-templating systems.
Setup
The setup for tempel is very simple. Here is my configuration for the package:
(use-package tempel
:ensure t
:demand t
;; Require trigger prefix before template name when completing.
:bind (("M-i" . tempel-complete) ;; Alternative tempel-expand
("M-S-i" . tempel-insert))
:init
;; Setup completion at point
(defun tempel-setup-capf ()
;; Add the Tempel Capf to `completion-at-point-functions'.
;; `tempel-expand' only triggers on exact matches. Alternatively use
;; `tempel-complete' if you want to see all matches, but then you
;; should also configure `tempel-trigger-prefix', such that Tempel
;; does not trigger too often when you don't expect it. NOTE: We add
;; `tempel-expand' *before* the main programming mode Capf, such
;; that it will be tried first.
(setq-local completion-at-point-functions
(cons #'tempel-expand
completion-at-point-functions)))
:hook
((conf-mode . tempel-setup-capf)
(prog-mode . tempel-setup-capf)
(text-mode . tempel-setup-capf))
:config
(setq tempel-path "~/.emacs.d/tempel-snippets.el"))
Next, create a temple-snippets.el file in your .emacs.d directory and type away.
Defining a snippet
In my tempel.snippets.el file, I have around 24 snippets. You can look at it on my emacs configuration. The structure of the file is like this:
desired-mode-for-snippet ;; (eg. fundamental, org, c++)
(snippet-name "snippet body")Top 5 Snippets
#1 - up
This is my most used snippet. I use it all the time for when I need to make a use-package declaration in my Emacs configuration.
(up "(use-package "p n> ":ensure t" n> (s configuration) q")")
#2 - today
today evaluates the native Emacs function format-time-string. This is a great example of how tempel can use existing functions in it's snippets.
(today (format-time-string "%Y-%m-%d"))
#3 - begin
Begin starts a LaTeX begin macro for formatting anything. When you type begin, it moves you to the brackets and then you can fill out both ends of the begin at once with equation, center, aligned, etc.
(begin "\\begin{" (s env) "}" r> n> "\\end{" (s env) "}")
#4 - mode
Emacs has a feature for adding local file variables with a prop line at the beginning of files. I use this to give a mode to files without an extension like scheme scripts I write.
(mode "-*- mode: " (s mode) " -*-")#5 - Programming-related snippets
These are things I would type anyway while programming that are condensed. They could probably be converted into abbrev-mode expansions, but I just cooked these up quickly while I was working.
sh-mode
(! & "#!/usr/bin/bash" n q)
perl-mode
(! & "#!/usr/bin/perl" n "use strict;" n "use warnings;" n n q)
c++-mode
(log "std::cout << \"" p "\" << std::endl;")Conclusion
Snippets/templates are a really useful way to speed up your text-editing. If you're going to repeat typing something a bunch, you might as well make a snippet for it.
Yasnippet
I used to use yasnippet (probably the most popular snippet package), but I realized it's not for me because I didn't like making a new file for every snippet. I was too lazy to figure out the syntax to make my own, so I switched to tempel. I could probably still use it, but I'll use what works.